CN1256721A - Method for controlling the AIF3 content in cryolite melts - Google Patents
Method for controlling the AIF3 content in cryolite melts Download PDFInfo
- Publication number
- CN1256721A CN1256721A CN99800131.7A CN99800131A CN1256721A CN 1256721 A CN1256721 A CN 1256721A CN 99800131 A CN99800131 A CN 99800131A CN 1256721 A CN1256721 A CN 1256721A
- Authority
- CN
- China
- Prior art keywords
- liquidus temperature
- rated value
- temperature
- alf
- records
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/20—Automatic control or regulation of cells
Abstract
The invention relates to a method for controlling the AlF3 content in cryolite melts for aluminium reduction, during which the temperature of the melt is measured. To be able to provide a highly accurate method which allows for aluminium reduction to be carried out at the lowest possible temperature, i.e. saving as much energy as possible, the invention provides for the Liquidus temperature to be measured and compared with a first setpoint value. AlF3 is added to the bath if the Liquidus temperature measured is higher than the first setpoint value, and the measured Liquidus temperature is compared with a second setpoint value which is lower than the first if the Liquidus temperature measured is lower than the first setpoint value. NaF or Na2CO3 is added to the bath if the Liquidus temperature measured is lower than the second setpoint value.
Description
The present invention relates to the cryolite melts AlF that a kind of control is used for aluminium reducing
3The method of content, the temperature of measurement melt in the method.
US-A-4,668,350 reported a kind of similar method.Disclosed method has utilized bath temperature and molten bath to form (NaF:AlF
3) between a kind of known relationship.From this relation, can form (NaF:AlF according to a kind of nominal
3) calculate the temperature rating in molten bath.Measure bath temperature, when bath temperature is higher than temperature rating, then add AlF
3Certainly, bath temperature is influenced by a series of other factorses also.
The present invention's purpose is to propose a kind of method very accurately, and the reduction of aluminium may be carried out under a kind of alap temperature, and is also energy-conservation as far as possible.
The present invention's purpose reaches by following manner: the liquidus temperature of measuring cryolite melts; The liquidus temperature that records and first rated value are relatively; If the liquidus temperature that records is higher than first rated value, then in the molten bath, add AlF
3If the liquidus temperature that records is lower than first rated value, the liquidus temperature that then records be lower than second rated value of first rated value relatively; If the liquidus temperature that records is lower than second rated value, then in the molten bath, add NaF or Na
2CO
3
Because the liquidus temperature of melt can be inferred the share of each component of melt very exactly, so the present invention's method can make the aluminium reducing process under energy-conservation as far as possible prerequisite, thereby also carries out under economic as far as possible prerequisite.The present invention also is included in the reverse comparison between rated value and the liquidus temperature observed value significantly, and the liquidus temperature that promptly records at first compares with second rated value, if the liquidus temperature that records is lower than this second rated value, then adds NaF or Na to bathing
2CO
3If the liquidus temperature that records is higher than second rated value, the liquidus temperature that then records compares with first rated value that is higher than second rated value, if the fluid temperature that records is higher than first rated value, then should add AlF in the molten bath
3For example, if the liquidus temperature that records less than second rated value, certainly with higher first rated value relatively be exactly unnecessary.If the liquidus temperature that records between two rated value, so just need not add any component that influences liquidus temperature.
In order to form buffer zone and to avoid adding the excessive response that causes, need two different rated value by compensation.
Except other factors, the temperature head between two rated value is relevant with the stability of aluminium reducing process; If process stabilization can be selected little temperature head.The liquidus temperature in molten bath is with all component is relevant, particularly with Al
2O
3And AlF
3Relevant.Therefore, the difference between two rated value also with AlF
3(or other component, as Al
2O
3) mode, amount and the accuracy added be relevant.For example, the amount of interpolation is littler, and difference is also little.Point type feeder (Point feeder) feed molar ratio center bar derailing switch (Centre bar breaker) or side operating groove (Sideworked cell) less amount and more accurate.Inter alia, the difference between first and second rated value is also relevant with melt control personnel's experience, and general rule is along with the empirical accumulation of operator, and it is littler that difference can become.
In principle, by adding AlF
3Can reduce the liquidus temperature of melt, by adding the liquidus temperature that NaF can improve melt.Add Na
2CO
3Also can improve liquidus temperature, because Na
2CO
3To the formation of NaF in the melt, improve the share of NaF thus, reduce AlF
3Share contribution is arranged.The too low AlF of the too high expression of too high liquidus temperature
3-concentration, and too low liquidus temperature is represented too high temperature AlF
3Concentration.The NaF or the Na that add
2CO
3Can with AlF
3Common formation sodium aluminum fluoride, thus make AlF
3Concentration reduce.At first, draw a rated value of liquidus temperature according to known phasor when considering the initial composition in molten bath, second rated value then formed definite according to the molten bath of hypothesis.US-A-4,668,350 have been described in detail the physical relationship between molten bath composition and the bath temperature.Therefore, can obtain clear and definite relation based on disclosure.
According to the present invention, should outside the molten bath, measure the cooling curve of a sample of melt and also measure liquidus temperature thus.Fluid temperature can be measured by other suitable method of also knowing for the professional in principle.
To narrate one embodiment of the present of invention below.
First rated value can calculate according to the average composition or actual composition the in molten bath.For example contain CaF by share
2Be 5%, Al
2O
3Be 3%, AlF
3Excessive is 12% molten bath (HalvorKvande; Metallurgy magazine (Journal of Metallurgy), November 1994, and liquidus temperature 22-) is 955 ℃, AlF
3Excessive is that 11% o'clock liquidus temperature is 960 ℃, AlF
3Excessive is that 13% o'clock liquidus temperature is 950 ℃.In other words, AlF
3Excessive variation 2%, liquidus temperature changes 10 ℃.Solheim's etc., light metal (LightMetals) 1955, S451-(The Minerals, Metals; Materials Society (mineral, metal and materialogy meeting), 1955) done similar calculating.For example, if first rated value is 960 ℃, and liquidus temperature is determined as 970 ℃, then AlF
3Excessively should improve 2%.
For stabilised bath, temperature rating (rated value) can reduce.Improve AlF thus
3Concentration, this just can improve current efficiency.If the molten bath becomes instability, liquidus temperature (rated value) will improve.The common available routine that has appropriate sensor of the stability in pond is controlled and is monitored.
Second rated value is except other factors, with Al
2O
3The mode that adds in the molten bath is relevant.Under the reinforced situation of automatic or point type, second rated value be approximately than low about 10 ℃ of first rated value, under center bar derailing switch or non-automatic reinforced situation, and low about 20 ℃ of second comparable first rated value of rated value.If the measured value of liquidus temperature is higher than first rated value, then should add AlF according to above-mentioned typical component
3If it is lower than second rated value, then should add NaF (or Na
2CO
3), and interpolation 3%NaF (by the molten bath total amount) can cause liquidus temperature to improve about 10 ℃.If second rated value is 950 ℃, and the liquidus temperature that records is 940 ℃, then should add 3%NaF by the molten bath total amount.
For example measuring can per two day or carry out every day.
Claims (2)
1. a control is used for the cryolite melts AlF of aluminium reducing
3The method of content, the temperature of measurement melt is characterized in that in this method, measures liquidus temperature; The liquidus temperature and first rated value that record are compared; If the liquidus temperature that records is higher than this first rated value, then in the molten bath, add AlF
3If the liquidus temperature that records is lower than first rated value, then relatively with liquidus temperature that records and second rated value that is lower than first rated value; If the liquidus temperature that records is lower than second rated value, then should in the molten bath, add NaF or Na
2CO
3
2. the method for claim 1 is characterized in that, at the cooling curve of a sample of molten bath external pelivimetry melt, and determines liquidus temperature thus.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19805619.2 | 1998-02-12 | ||
| DE19805619A DE19805619C2 (en) | 1998-02-12 | 1998-02-12 | Process for controlling the AlF¶3¶ content in cryolite melts |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1256721A true CN1256721A (en) | 2000-06-14 |
| CN1144900C CN1144900C (en) | 2004-04-07 |
Family
ID=7857426
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB998001317A Expired - Fee Related CN1144900C (en) | 1998-02-12 | 1999-02-10 | Method for controlling the AIF3 content in cryolite melts |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US6183620B1 (en) |
| CN (1) | CN1144900C (en) |
| AU (1) | AU3027399A (en) |
| BR (1) | BR9904777A (en) |
| CA (1) | CA2285992A1 (en) |
| DE (1) | DE19805619C2 (en) |
| FR (1) | FR2774701B1 (en) |
| NO (1) | NO994951L (en) |
| WO (1) | WO1999041432A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2821363B1 (en) | 2001-02-28 | 2003-04-25 | Pechiney Aluminium | METHOD FOR REGULATING AN ELECTROLYSIS CELL |
| FR2821364B1 (en) | 2001-02-28 | 2004-04-09 | Pechiney Aluminium | METHOD FOR REGULATING AN ELECTROLYSIS CELL |
| EP1344847A1 (en) * | 2001-12-03 | 2003-09-17 | Alcan Technology & Management AG | Regulating of aluminium electrolysis cells |
| US7255783B2 (en) | 2003-08-21 | 2007-08-14 | Alcoa Inc. | Use of infrared imaging to reduce energy consumption and fluoride consumption |
| US6942381B2 (en) * | 2003-09-25 | 2005-09-13 | Alcoa Inc. | Molten cryolitic bath probe |
| CN101270485B (en) * | 2008-05-10 | 2010-06-16 | 中国铝业股份有限公司 | Control method for electroanalysis of degree of superheat |
| RU2651931C2 (en) * | 2016-06-08 | 2018-04-24 | Общество с ограниченной ответственностью "Объединенная Компания РУСАЛ Инженерно-технологический центр" | Device and method for determination of electrolyte composition |
| CA3172097A1 (en) * | 2020-06-09 | 2021-12-16 | Alcoa Usa Corp. | Methods of producing aluminum fluoride from cryolite bath |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA716167B (en) * | 1970-09-22 | 1972-05-31 | Comalco Ltd | Production of aluminium |
| NO135034B (en) * | 1975-04-10 | 1976-10-18 | Norsk Hydro As | |
| DE3564825D1 (en) * | 1985-03-18 | 1988-10-13 | Alcan Int Ltd | Controlling alf 3 addition to al reduction cell electrolyte |
| FR2620738B1 (en) * | 1987-09-18 | 1989-11-24 | Pechiney Aluminium | PROCESS FOR REGULATING THE ACIDITY OF THE ELECTROLYSIS BATH BY RECYCLING THE FLUORINATED PRODUCTS EMITTED BY THE HALL-HEROULT ELECTROLYSIS TANKS |
| EP0455590B1 (en) * | 1990-05-04 | 1995-06-28 | Alusuisse-Lonza Services Ag | Regulating and stabilizing the AlF3-content of aluminium electrolysis cells |
| DE4433685C2 (en) * | 1994-09-21 | 1997-02-13 | Heraeus Electro Nite Int | Sensor arrangement for temperature measurement, temperature measuring device and method |
-
1998
- 1998-02-12 DE DE19805619A patent/DE19805619C2/en not_active Expired - Fee Related
-
1999
- 1999-02-10 CA CA002285992A patent/CA2285992A1/en not_active Abandoned
- 1999-02-10 BR BR9904777-2A patent/BR9904777A/en not_active Application Discontinuation
- 1999-02-10 CN CNB998001317A patent/CN1144900C/en not_active Expired - Fee Related
- 1999-02-10 WO PCT/EP1999/000846 patent/WO1999041432A1/en active Application Filing
- 1999-02-10 AU AU30273/99A patent/AU3027399A/en not_active Abandoned
- 1999-02-12 FR FR9901703A patent/FR2774701B1/en not_active Expired - Fee Related
- 1999-10-11 NO NO994951A patent/NO994951L/en not_active Application Discontinuation
- 1999-10-12 US US09/416,327 patent/US6183620B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO1999041432A1 (en) | 1999-08-19 |
| NO994951D0 (en) | 1999-10-11 |
| NO994951L (en) | 1999-10-11 |
| BR9904777A (en) | 2000-03-08 |
| CA2285992A1 (en) | 1999-08-19 |
| FR2774701B1 (en) | 2000-06-23 |
| FR2774701A1 (en) | 1999-08-13 |
| DE19805619A1 (en) | 1999-09-09 |
| AU3027399A (en) | 1999-08-30 |
| CN1144900C (en) | 2004-04-07 |
| DE19805619C2 (en) | 2002-08-01 |
| US6183620B1 (en) | 2001-02-06 |
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| C14 | Grant of patent or utility model | ||
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| CF01 | Termination of patent right due to non-payment of annual fee |